1. Field of the Invention
The invention relates to a method for detecting failure of injectors in an internal combustion engine, an engine control unit for an internal combustion engine as well as a system to carry out the method for failure detection.
2. Description of the Related Art
Methods for detecting failure of fuel injectors are known in the prior art. One such method is known from U.S. Pat. No. 5,303,158 A for recognition of abnormal combustion events in cylinders of an internal combustion engine, whereby a failed injector can be determined from an anomalous combustion event. Within the scope of the known method a speed signal of the internal combustion engine is Fourier-transformed and amplitudes within predetermined frequency ranges of the thus obtained spectra are compared in order to detect an anomalous combustion event. If such an event is detected, the method uses separate process steps to find out in which cylinder the anomalous combustion is occurring. For this purpose an anomalous combustion is forced respectively in the individual cylinders and amplitudes in predetermined frequency ranges of the thus obtained spectra are again compared with each other, whereby the results of the comparison are compared with corresponding results from the spectra received previously without forced anomalous combustion. This demonstrates that the method is complicated and cumbersome, in particular because after recognition of an anomalous combustion, such forced anomalous combustion must be forced sequentially in each cylinder, so that it can be determined in which cylinder the anomalous combustion event is occurring. The comparison of the amplitudes in predefined frequency ranges of the various spectra is also expensive and cumbersome.
What is needed in the art is a method with which injector failure can be simply and quickly detected and a failed injector identified during normal operation of the engine. An engine control unit which is designed to perform the method is also needed, as well as a system with the help of which the method can be implemented.